As the fight against climate change increasingly focuses on food waste as a source of planet-warming emissions, entrepreneurs are coming up with crafty ways to reduce the glut of produce that gets thrown.

About a third of food produced each year is never eaten either because it is spoiled after harvest and during transportation, or thrown away by shops and consumers, according to U.N. Food and Agriculture Organization (FAO).

Discarded food ends up in landfills where it rots, releasing harmful greenhouse gasses, while the water, energy and fuel needed to grow, store and transport it is wasted.

Speaking at conference in Milan this week, former U.S. President Barack Obama said innovation was key to reduce emissions from agriculture and achieve “a sustainable food future” with enough for everyone to eat.

“Part of this is also going to be wasting less food … especially when nearly 800 million men, women and children worldwide face the injustice of chronic hunger and malnutrition,” he said.

Obama’s address was the climax of a four-day food industry conference in the Italian city.

Here are some of the best food waste innovations showcased at the event:

Demetra

Produced by Italian biotechnology start-up Green Code, Demetra is a natural post-harvest treatment that extends fruit’s shelf life.

It consists of a mixture of plant extracts that stops fruit from ripening — delaying the rotting process — while retaining its nutrients, said Green Code co-founder Emiliano Gentilini.

“As a consequence food can be kept much longer,” Gentilini told the Thomson Reuters Foundation.

The mixture is applied on fruit by nebulization or immersion but the company is developing an easier, dry application method for developing countries.

Demetra was awarded a 2017 U.N. award for “Innovative Ideas and Technology on Agribusiness” on Wednesday.

Winnow

British start-up Winnow helps commercial chefs cut waste by measuring just what they throw from the kitchen every day.

It provides them with a smart scale connected to a tablet that weights all waste. Staff tap on the screen what is being thrown and receive detailed reports on waste patterns and costs that allow chefs to make adjustments.

“Chefs systematically under-estimate how much food they waste,” said Marc Zornes, co-founder of Winnow.

On average, he said large kitchens bin between 10 and 20 percent of food they buy. Zornes said restaurants using his technology could save up to eight percent on food costs and cut waste by more than half.

RISE

New York-based food tech startup RISE uses spent barley, a by-product of beer production, to make flour for bread, pizza, cookies and other baked goods.

In the United States currently $1.2 billion a year is spent to send to landfill about 5 million tonnes (5.5 million tons) of grains that are mashed and boiled to make beer, according to the company.

RISE charges a fee to collect spent barley from breweries, which it then processes into flour to sell to commercial bakers, chefs and food manufacturers, said co-founder Jessica Aguirre.

The company currently operates from a Brooklyn kitchen but Aguirre said the model could be easily replicated elsewhere.

“There are breweries everywhere,” she told the Thomson Reuters Foundation. “Our technology is very simple and can be easily implemented in developing countries,” she added.

Other firms such as Coffee Flour and Renewal Mill use similar processes to make food from ingredients left over by the industrial production of items such as coffee and soy milk.